1. FIELD OF THE INVENTION
This invention relates to a bale opener, particularly a travelling bale opener which is propelled back and forth along a series of fiber bales and which has an opening device proper that detaches fiber tufts from the top bale surfaces the bale opener travels.
2. DESCRIPTION OF THE RELATED ART
The opening device has at least one rapidly rotating opening or detaching roll supported horizontally in a downwardly open housing which is mounted on a bale opener tower and which, in cantilever fashion, projects horizontally laterally of the tower, in a direction transverse to the travelling (working) direction of the bale opener. As the height of the fiber bales is reduced during the fiber tuft detaching operation, the cantilever housing, together with the opening device, is periodically moved downwardly with respect to the tower of the bale opener to maintain the opening roll (or opening rolls) in engagement with the bale surfaces.
The opening roll has a plurality of spikes or teeth (detaching elements) on its surface. The detaching elements form axially spaced groups; the detaching elements in each group are arranged circumferentially. Each group of detaching elements may be formed on the periphery of discs, axially spacedly secured to a core (hub) of the opening roll. Underneath the opening roll or opening rolls a grate may be positioned which is formed of a plurality of spaced grate bars oriented parallel to the direction of travel (working direction) of the bale opener. The grate bars which extend in the space between adjoining groups of detaching elements, engage the top fiber bale surfaces and thus stabilize the fiber bales.
As the opening device is moved along the fiber bales and the detaching operation is in progress, in the upper bale surfaces side-by-side extending alternating furrows and ridges are formed, due to the spacing between the groups of detaching elements of the opening roll. Such ridges can be ablated only with difficulty, because the detaching elements do not reach the ridges formed of the compressed fiber material. Rather, the material which forms the ridges is torn out by being entrained by the fiber material engaged directly by the detaching elements. The ridges may be removed only gradually in several passes of the bale opener.
To provide for a more rapid elimination of the ridges and furrows during the detaching operation, it has been known to periodically shift the opening roll, relative to its supporting housing, in a horizontal direction, transversely to the working direction, to an extent which at least approximately equals one-half the axial center-to-center distance between adjoining groups of detaching elements. In case a grate is provided, the grate and the opening roll reciprocate as a unit. Such a construction is disclosed, for example, in U.S. Pat. No. 4,281,437, issued Aug. 4, 1981.
In the solution according to the described prior art, a horizontal, transverse, axial mobility of the opening roll proper relative to its supporting housing has to be provided. Such arrangements are particularly complex if, for example, several parallel-arranged opening (detaching) rolls are provided.